/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.nutch.scoring;

import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.conf.Configured;
import org.apache.nutch.indexer.NutchDocument;
import org.apache.nutch.plugin.Extension;
import org.apache.nutch.plugin.ExtensionPoint;
import org.apache.nutch.plugin.PluginRepository;
import org.apache.nutch.plugin.PluginRuntimeException;
import org.apache.nutch.storage.WebPage;
import org.apache.nutch.util.ObjectCache;

/**
 * Creates and caches {@link ScoringFilter} implementing plugins.
 * 
 * @author Andrzej Bialecki
 */
public class ScoringFilters extends Configured implements ScoringFilter {

	private ScoringFilter[] filters;

	public ScoringFilters(Configuration conf) {
		super(conf);
		ObjectCache objectCache = ObjectCache.get(conf);
		String order = conf.get("scoring.filter.order");
		this.filters = (ScoringFilter[]) objectCache
				.getObject(ScoringFilter.class.getName());

		if (this.filters == null) {
			String[] orderedFilters = null;
			if (order != null && !order.trim().equals("")) {
				orderedFilters = order.split("\\s+");
			}

			try {
				ExtensionPoint point = PluginRepository.get(conf)
						.getExtensionPoint(ScoringFilter.X_POINT_ID);
				if (point == null)
					throw new RuntimeException(
							ScoringFilter.X_POINT_ID + " not found.");
				Extension[] extensions = point.getExtensions();
				HashMap<String, ScoringFilter> filterMap = new HashMap<String, ScoringFilter>();
				for (int i = 0; i < extensions.length; i++) {
					Extension extension = extensions[i];
					ScoringFilter filter = (ScoringFilter) extension
							.getExtensionInstance();
					if (!filterMap.containsKey(filter.getClass().getName())) {
						filterMap.put(filter.getClass().getName(), filter);
					}
				}
				if (orderedFilters == null) {
					objectCache.setObject(ScoringFilter.class.getName(),
							filterMap.values().toArray(new ScoringFilter[0]));
				} else {
					ScoringFilter[] filter = new ScoringFilter[orderedFilters.length];
					for (int i = 0; i < orderedFilters.length; i++) {
						filter[i] = filterMap.get(orderedFilters[i]);
					}
					objectCache.setObject(ScoringFilter.class.getName(),
							filter);
				}
			} catch (PluginRuntimeException e) {
				throw new RuntimeException(e);
			}
			this.filters = (ScoringFilter[]) objectCache
					.getObject(ScoringFilter.class.getName());
		}
	}

	/** Calculate a sort value for Generate. */
	@Override
	public float generatorSortValue(String url, WebPage row, float initSort)
			throws ScoringFilterException {
		for (ScoringFilter filter : filters) {
			initSort = filter.generatorSortValue(url, row, initSort);
		}
		return initSort;
	}

	/**
	 * Calculate a new initial score, used when adding newly discovered pages.
	 */
	@Override
	public void initialScore(String url, WebPage row)
			throws ScoringFilterException {
		for (ScoringFilter filter : filters) {
			filter.initialScore(url, row);
		}
	}

	/** Calculate a new initial score, used when injecting new pages. */
	@Override
	public void injectedScore(String url, WebPage row)
			throws ScoringFilterException {
		for (ScoringFilter filter : filters) {
			filter.injectedScore(url, row);
		}
	}

	@Override
	public void distributeScoreToOutlinks(String fromUrl, WebPage row,
			Collection<ScoreDatum> scoreData, int allCount)
			throws ScoringFilterException {
		for (ScoringFilter filter : filters) {
			filter.distributeScoreToOutlinks(fromUrl, row, scoreData, allCount);
		}
	}

	@Override
	public void updateScore(String url, WebPage row,
			List<ScoreDatum> inlinkedScoreData) throws ScoringFilterException {
		for (ScoringFilter filter : filters) {
			filter.updateScore(url, row, inlinkedScoreData);
		}
	}

	@Override
	public float indexerScore(String url, NutchDocument doc, WebPage row,
			float initScore) throws ScoringFilterException {
		for (ScoringFilter filter : filters) {
			initScore = filter.indexerScore(url, doc, row, initScore);
		}
		return initScore;
	}

	@Override
	public Collection<WebPage.Field> getFields() {
		Set<WebPage.Field> fields = new HashSet<WebPage.Field>();
		for (ScoringFilter filter : filters) {
			Collection<WebPage.Field> pluginFields = filter.getFields();
			if (pluginFields != null) {
				fields.addAll(pluginFields);
			}
		}
		return fields;
	}
}
